Do I attempt to dismantle the wall or get a cherrypicker to work form the top of the stack?

I live in a 30s semi-detached with 4 original flues - 2 downstairs and 2 in the upstairs bedroom - that culminate into one chimney stack with two flues. Somewhere in the top 4 meters of the chimney, we have a BIG bees' nest. The roof is tiled, pitched and at least 2 meters above the roof line. A number of experts, from conservationists to exterminators, have looked and failed to figure out how to remove the nest. With 500 bees having come into the sitting at one time, I am getting desperate to get rid of the bees and the honeycomb. I am no expert on building or bees, but wanted to run this idea past you and get your thoughts:

1. I know they are in the top 4 meters because i used drain clearing rods and a webcam from the fireplace to look up the first 8 meters - couldn't get further due to the angle.
2. So, one plan is to go into the attic, and drill a few holes to insert calming agent/poison (whatever experts dictate) to lower risk of getting stung.
3. Then, get a builder to safely remove bricks to open a window where we can get at the hive and honeycomb and scrape it out of the chimney.
4. Once cleared, fill in the hole appropriately.

Would be really interested in whether any of you think this is possible and how much such a project might cost? My other option is to get a cherry picker and work from the top of the chimney, but this is likely to cost at least 500-700 quid and access will be limited. Thank you all!

PS I ought to say that we in no way want to kill the bees, but at the moment, involved bee keepers and bee associations do not see any possible way of removing them unharmed. Numerous approaches in working from the mouth of the fireplaces have been undertaken to no avail.

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